This invention generally relates to devices for inspecting the condition of wires and associated insulation and seals determine the quality or characteristics of each.
Wire strip inspection devices are well known and used in the industry in processing machines to monitor the quality of wires used in making electrical connections. The typical concern is to verify that the insulation on the wire has been properly removed. Conventional wire strip inspection devices include contact sensors where the exposed, conductive portion of the wire makes contact with two mechanical plates to form a connection that confirms that the insulation has been removed.
Other types of sensors have been utilized that do not require contact with the conductive portion of the wire. In conventional non-contact sensors, the wire is moved through a sensing window. The sensor head is mechanically positioned or aligned in the path of the insulation shoulder so that the insulation shoulder passes through the sensing window. Two sensing beams are typically utilized and positioned so that the insulation interrupts the first beam while the exposed conductive portion interrupts the second beam. A determination is made based upon a relative percentage between pulse width signals generated when the wire passes through the beams.
As an example, if the beam that is interrupted by the insulation is interrupted for ten milliseconds and the beam that is interrupted by the conductive portion is interrupted for six milliseconds, a relative percentage of 60% is determined. If the expected result should be 60%, then the wire strip is confirmed to be acceptable. Most systems have acceptable tolerance levels to accommodate slight variations.
Previously used sensing devices, however, are not without shortcomings and drawbacks. For example, mechanical setup is required to specifically accommodate any change in the expected strip length of the wire. Moreover, an operator typically is required to utilize trial and error to mechanically adjust the sensor over the travel position of the wire so that the individual beams are incident on the expected portion of the wire. Additionally, the wire-processing machine must be precisely calibrated to move each wire sample through the sensor at the exact same position or erroneous results are achieved.
Existing sensor arrangements do not provide sufficiently economical operation because of the large amount of operator input and sophistication that is required. Moreover, the large amount of precise and tedious adjustment required to accommodate different wire sizes, tolerances and seal applications introduces additional down time of a machine and the associated costs in loss of production time.
Additionally, previous devices are not capable of detecting all of the characteristics of a wire that ideally are monitored as part of the inspection process. For example, previously used sensors may be capable of detecting the presence of a seal on a wire but cannot determine the seal""s orientation or condition.
Accordingly, there is a need for an improved wire inspection device that has greater capabilities, is more effective and does not require a large amount of operator input or adjustment. This invention provides such a system and avoids the shortcomings and drawbacks of the prior art discussed above.
This invention is a device for inspecting wires to determine selected characteristics of the wire such as an amount of insulation that has been removed, the condition of the exposed conductive portion of the wire, a location of the insulation shoulder relative to an end point on the conductive portion of the wire, a location of a seal member on the wire and an orientation and condition of the seal member. A device designed according to this invention is capable of determining any one or several of the wire characteristics, depending on the needs of a particular situation.
A device for determining selected characteristics of a wire that is designed according to this invention includes several components. A plurality of sensing elements are arranged in a desired orientation. Each of the sensing elements produces its own output. A source of radiation, which preferably is a laser beam, is positioned to irradiate the sensing elements. As a wire passes by the sensing elements and interrupts the radiation, each sensing element output indicates the amount of radiation that has been blocked by the wire passing each sensing element. A controller receives the outputs from the sensing elements and responsively determines the selected characteristics of the wire.
In one example, the sensing elements are aligned in a straight array and a masking element with a straight opening is placed near the sensing elements to enhance the resolution of the system. The opening in the masking element directs the radiation onto the sensing elements in a manner that facilitates more accurate analysis of a wire sample.